Tagged PDF

A PDF document that contains semantic structure tags defining the logical reading order, headings, paragraphs, lists, tables, and figures — enabling screen readers and other assistive technologies to navigate and interpret the content meaningfully. Without tags, a PDF is essentially a flat image of text with no structural information, forcing screen readers to guess the reading order and making navigation impossible. The PDF/UA (Universal Accessibility) standard specifies requirements for tagged PDFs. Despite being essential for accessibility, the vast majority of scholarly and business PDFs remain untagged.